Generally, a conventional driving circuit for a liquid crystal display device is in a form of an external integrated circuit module, such as the commonly used Tape Automated Bonding (TAB) packaging structure. With the development of a thin film transistor semiconductor process, the popularization of a narrow frame technique and the demands for reduced costs, integrated circuit technology based on the peripherals of an LCD TV panel becomes a focus of research, wherein a typical application is the Gate Driver on Array (GOA).
Using an array liquid crystal display device manufacturing procedure, the GOA driving circuit provides a gate scanning driving signal circuit on an array substrate to conduct drive scan line by line on pixel units. The GOA driving circuit not only enables to cut down the welding process of an external integrated circuit to improve the integration, but also boosts the production capacity and lowers the cost, and thus has become a trend in recent years. Further, with the popularization of the narrow frame technique, large-size liquid crystal display devices also need relevant technology support, and thus more requirements are made on the driving circuit.
Because a GOA driving unit for operating a line of pixels remains on for merely several tens of microseconds in one frame time but remains off for a fairly longer time, a pull-down maintaining unit remains in a prolonged on-state, which demands a high stability. In the prior art, an overall product reliability is generally enhanced by means of an increased channel length of key transistors in the pull-down maintaining unit, since as the channel length of the transistors increases, the time of a high-temperature and high-humidity test for the GOA circuit increases. For transistors having different channel lengths, however, the problem of uneven films would emerge when photomasks having a same penetration are used for exposure, while the cost would rise when photomasks having different penetrations are used.
The present disclosure provides an improved technical solution to the above mentioned problem so as to increase the circuit reliability.